1. Field of the Invention
The present invention relates to a display device for modulating a light beam to display a picture, and more particularly to a transmissive display device using a micro light modulator that is capable of improving light efficiency.
2. Description of the Related Art
There have been studies made of various flat panel display devices which are expected to be next generation display devices. Such flat panel display devices include a liquid crystal display (LCD) and a plasma display panel (PDP) using a gas discharge, etc. which are now available in the market. The LCD has disadvantages in that it has a narrow viewing angle and a slow response speed and that its fabrication process is complicated because thin film transistors (TFT""s), used as switching devices and electrodes, etc. are formed by a semiconductor fabrication process. On the other hand, the PDP has an advantage in that its fabrication process is simple, and can provide a large-dimension screen. However, the PDP has a disadvantage in that it has low discharge and luminescence efficiencies.
Accordingly, studies have been conducted toward the development of a novel display device capable of overcoming such problems in the flat panel devices. Recently, there has been suggested a transmissive display device that is provided with a micro light modulator for each pixel using a micro electromechanical system (MEMS) as an ultra-fine processing technique so as to display a picture.
FIG. 1A and FIG. 1B are schematic section views showing a structure of a transmissive display device using a micro light modulator that has been disclosed in Korean Patent Application No. 10-1999-0043554 filed on Oct. 8, 1999 by the Applicant. Referring to FIGS. 1A and 1B, the transmissive display device includes a plurality of lower stationary electrodes 12 provided on a substrate 13 in line with and at a desired distance from each other, and a plurality of movable electrodes 11 overlapping with the lower stationary electrodes 12 in response to a voltage. The lower stationary electrodes 12 are formed in a stripe shape on the substrate 13. Each of the upper movable electrodes 11 has each end fixed to the substrate and has a center portion floated, by a desired distance, from the substrate 13. The lower stationary electrodes 12 and the upper movable electrodes 11 are controlled by an electrical signal and function to open and close a light path by the effect of static electricity occurring between each other depending on whether the device is in a display state or in a non-display state.
In the non-display state as shown in FIG. 1A, a desired voltage is applied to the lower stationary electrodes 12 and the upper movable electrodes 11. Then, since an attraction caused by the presence of static electricity on the lower stationary electrodes 12 and the upper movable electrodes 11, the upper movable electrodes 11 contact the lower stationary electrodes 12 adjacent thereto. As a result of the contact between, the lower stationary electrodes 12 and the upper movable electrodes 11 the light from a back light is shut off (not shown).
On the other hand, in the display state as shown in FIG. 1B, no voltage is applied to the lower stationary electrodes 12 and the upper movable electrodes 11. Since the upper movable electrodes 11 are returned to their primary states by their elastic forces, they are suspended at a distance from the substrate 13 and the lower stationary electrodes 12. At this time, a light path is provided between each lower stationary electrode 12 and each upper movable electrode 11. A light from a backlight (not shown) is transmitted, via the light path, to a display screen to display a picture or an image.
In such a transmissive display device using a micro light modulator, a light from the back light is inputted at a desired inclined angle (i.e., 60xc2x0 to 80xc2x0) with respect to the substrate 13. Thus, it is necessary to control the light path vertically with respect to the display screen so that an observer positioned perpendicularly to the display screen can view a picture at a higher brightness.
To this end, as shown in FIG. 2, an upper substrate (not shown) includes first and second prism sheets 16a and 16b for changing a path of a light transmitting obliquely between the lower stationary electrodes 12 and the upper movable electrodes 11 vertically with respect to the display screen, and a diffusion sheet 18 provided on the prism sheets 16a and 16b. A prism pattern having a triangular section is formed at each of the first and second prism sheets 16a and 16b in a direction perpendicular to each other. The diffusion sheet 18 functions to diffuse light inputted from the second prism sheet 16b. 
Accordingly, it is an object of the present invention to provide a transmissive display device using a micro light modulator that is adaptive for improving light efficiency.
In order to achieve these and other objects of the invention, a transmissive display device using a micro light modulator according to an embodiment of the present invention includes light-path converting members, being provided on stationary members, for changing the path of a light inputted obliquely through stationary members and movable members vertically with respect to a display screen.
A transmissive display device using a micro light modulator according to another embodiment of the present invention includes light-path converting members, being provided on stationary members, for changing the path of a light inputted obliquely between stationary members and movable members vertically with respect to a display screen and for constantly keeping a distance between a rear substrate and a front substrate opposed to each other.
A transmissive display device using a micro light modulator according to still another embodiment of the present invention includes light-path converting members, being provided on stationary members, for changing the path of a light inputted obliquely between stationary members and movable members vertically with respect to a display screen, wherein an angle of an incidence surface at one side of the light-path converting members is set to more than 52xc2x0 on the basis of a display screen.